Multiple unit and unit recording from osmoreceptive brain areas related to thirst is a neglected research area. Prior research on osmoreceptors has been almost entirely confined to recording from neurons in and around the supraoptic nucleus. Evidence from experiments employing lesions or hypertonic microinjection point to the lateral preoptic area as site of osmoreceptors for thirst. We have multiple unit and unit recording data that support this hypothesis. We are following up these positive findings with brain recording experiments designed (a) tt isolate osmoreceptors through recording from "islands" of osmosensitivecells in the lateral preoptic area; (b) to record from various selected brain areas along with the lateral preoptic area during hyperosmotic challenge (e.g., septal area, cingulate cortex, zona incerta, reticular formation, lateral hypothalamus, hippocampus, and amygdala); (c) to study interactions between systemic osmotic alterations and oropharangeal (especially lingual) stimulation, revealed in brain recordings; (d) in chronic experiments to use the information from the acute experiments to study correlations between recorded brain activity and thirst-related behavior; (e) to make full use of our facilities for autonomic recording (e.g., continuous blood pressure recording in the rat) for monitoring the effectsof physiological interventions.